History Main / APupilOfMineUntilHeTurnedToEvil

* A slight variation in ''ComicBook/TheAmazingScrewOnHead'': Emperor Zombie used to be Head's manservant until he turned to evil.
* Franchise/{{Batman}} has Jason Todd, the second Robin who died and came back later wearing a different mask, although whether he wants to (lethally) simply stop all crime from Gotham or murder the whole Batfamily depends on the writer. Come the New 52, Jason has mostly made a HeelFaceTurn, though his relationship with the rest of the family is still strained and he's still prone to lethal force when sufficiently pushed.
* Subverted in ''ComicBook/BatmanLastKnightOnEarth'', as over the course of the story, the characters speculate that Omega was a protege of the original Batman who went rogue and betrayed his ideals, [[spoiler:but while technically the latter is true, Omega didn't betray Bruce -- as it turns out that Omega is actually [[FallenHero the original Bruce Wayne himself]].]]
* Inverted in ''ComicBook/DeathVigil'' by [[spoiler: Wulf, who was Sam's mentor in the Vigil. Wulf was a loyal and respected member of the Vigil for centuries, but then his gifted surrogate daughter was killed in an accident and Bernie was unable to do anything for her. Although we never hear her reasoning from ''Bernie's'' perspective, Wulf claims she refused him, and [[FaceHeelTurn didn't take it well]]]].
* In ''ComicBook/DoctorStrange'' titles, it's [[DependingOnTheWriter not quite clear]] whether the Ancient One's other disciple Baron Mordo was this or a DeceptiveDisciple. [[TheAtoner Maybe a little of both]].
* ''ComicBook/TheQuestForTheTimeBird'' has Bulrog; a former student of the knight Bragon who turned mercenary and eventually ends up seeking vengeance on his master.
* In ''ComicBook/MoonKnight'', Jeff Wilde, the son of villain the Midnight Man, takes on the superheroic persona of Midnight and attaches himself as sidekick to the reluctant Marc Spector. The HYDRA breakaway sect Secret Empire capture him and subject him to UnwillingRoboticisation, causing him to turn AxCrazy.

* ''WebAnimation/{{RWBY}}'': {{Inverted|Trope}}. After the previous leader stepped down, the White Fang changed from a faunus rights organization into a terrorist organization. As one of the leaders, [[Characters/RWBYAdamTaurus Adam Taurus]] was in a position to school Blake in the new way of doing things. Blake described Adam's descent into extremism as gradual, justifying violence as accidents, then self-defense, then necessary. When the pair take part in a train heist, Adam intends to blow the train; upon asking about the innocent humans on board, Blake is concerned to hear Adam reply "What about them?", finally seeing how far he fell from grace. As a result, she abandons Adam, rescuing the train of people in the process, and goes on the run from the White Fang. She decides to attend to Beacon Academy and train to become a Huntress, someone who protects the people from harm. [[spoiler:For betraying him, Adam vows to destroy everything she ever loved, guilt-tripping her into feeling like she's to blame for his actions in destroying Beacon Academy and maiming her teammate, Yang. It eventually leads Blake to vow to take back the White Fang from him and restore it to its former peaceful model.]]

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%%%% This trope is represented in the Pantheon/TropePantheons by Gharnef of ''VideoGame/FireEmblemShadowDragonAndTheBladeOfLight'', in the Hall of Pantheon/AlignmentChanges.
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[[quoteright:299:[[Franchise/StarWars https://static.tvtropes.org/pmwiki/pub/images/evil_pupil.png]]]]
[[caption-width-right:299:[[CallForward "Why do I get the feeling you're going to be the death of me?"]]]]
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* ''WebAnimation/{{RWBY}}'': {{Inverted|Trope}}. After the previous leader stepped down, the White Fang changed from a faunus rights organization into a terrorist organization. As one of the leaders, Adam was in a position to school Blake in the new way of doing things. Blake described Adam's descent into extremism as gradual, justifying violence as accidents, then self-defense, then necessary. When the pair take part in a train heist, Adam intends to blow the train; upon asking about the innocent humans on board, Blake is concerned to hear Adam reply "What about them?", finally seeing how far he fell from grace. As a result, she abandons Adam, rescuing the train of people in the process, and goes on the run from the White Fang. She decides to attend to Beacon Academy and train to become a Huntress, someone who protects the people from harm. [[spoiler:For betraying him, Adam vows to destroy everything she ever loved, guilt-tripping her into feeling like she's to blame for his actions in destroying Beacon Academy and maiming her teammate, Yang. It eventually leads Blake to vow to take back the White Fang from him and restore it to its former peaceful model.]]

* ''VideoGame/TheLegendOfZeldaTheMinishCap'': Said by Ezlo about Vaati, who "became enchanted by the wickedness in the hearts of men."
* ''VideoGame/TheLegendOfZeldaSpiritTracks'': Byrne was an apprentice of Anjean in the Tower of Spirits. He desired power from the good spirits, and when he was not granted it, he left and reached out to serve the Demon King Malladus.

[[caption-width-right:299:[[Film/AttackOfTheClones "Why do I get the feeling]] [[CallForward you're going to be]] [[Film/ANewHope the death of me?"]]]]

* Kuvira of ''WesternAnimation/TheLegendOfKorra'' was once a promising apprentice of Suyin Bei Fong that she treated as one of her own children and was Captain of the guard of Zaofu. After the fall of the Earth Kingdom due to the events of Book 3, the two had a falling out over whether or not Zaofu should militarily pacify the now-fractured Earth Kingdom. Kuvira eventually took Suyin's elder son, her engineer, the security forces as well as Zaofu's richest residents to form what eventually became the [[TheEmpire Earth Empire]].

'''Obi-Wan Kenobi:''' A young Jedi named Darth Vader, who was a pupil of mine until he turned to evil, helped the Empire hunt down and destroy the Jedi Knights. [[MetaphoricallyTrue He betrayed and murdered your father]].

** The TropeNamer is a line in ''Star Wars Episode IV: Film/ANewHope'', about how Obi-Wan describes Darth Vader.
--->'''Luke Skywalker:''' How did my father die?
--->'''Obi-Wan Kenobi:''' A young Jedi named Darth Vader, who was a pupil of mine until he turned to evil, helped the Empire hunt down and destroy the Jedi Knights. [[MetaphoricallyTrue He betrayed and murdered your father]].

** And now gone full circle in ''Film/TheForceAwakens'' with Kylo Ren, one of Luke's students ([[spoiler:and his nephew by way of Han and Leia, whose real name is Ben Solo]]), going to the Dark Side ([[spoiler:in part thanks to his obsession with his grandfather, the TropeNamer]]), slaughtering his fellow students, and serving the [[TheRemnant First Order]] in an attempt to defeat the New Republic. Ren then [[spoiler:kills Han]]. [[FromBadToWorse Then, things get worse]] in ''Film/TheLastJedi'', when [[spoiler:[[TheStarscream Kylo decides to kill Supreme Leader Snoke]] and [[KlingonPromotion makes himself the new Supreme Leader]].]]

-->-- '''Tigress''' about '''Tai Lung''', ''WesternAnimation/KungFuPanda''

* In ''WesternAnimation/KungFuPanda'', Tai Lung was not only Shifu's first pupil, but also his [[UsedToBeASweetKid adopted son]], who Shifu pushed to excel at all costs, believing that he was training him to be [[TheChosenOne the Dragon Warrior.]] Unfortunately, this fostered an obsession and {{pride}} in Tai Lung that made him totally unworthy. Tai Lung's FaceHeelTurn was a direct result of this rebuke and their screwed up relationship.

* Sauron, the principle antagonist of Tolkien's ''Literature/TheLordOfTheRings'' trilogy, was a Maia in the First Age under the tutelage of the Vala Aulë the Smith, and went by the name Mairon, before Melkor the Morgoth corrupted him to his cause and made him his lieutenant. When Morgoth was defeated, Sauron essentially became self-employed and sought to dominate Middle-Earth himself.

[[caption-width-right:299:[[Film/AttackOfTheClones "Why do I get the feeling]] [[CallForward you're going to be the death of me?"]]]]

Compare DeceptiveDisciple (when the student was [[EvilAllAlong evil the whole time, just pretending not to be]]), EvilFormerFriend, FallenHero, MerlinAndNimue, UsedToBeASweetKid, and TheParagonAlwaysRebels.

* [[HeroKiller Garou]] from ''Webcomic/OnePunchMan'' was once the most promising student of [[OldMaster Bang]], the Rank 3 S-Class Hero. He then snaps one day, destroys the rest of the dojo, and begins hero hunting. Eventually he becomes so terrifyingly powerful that [[spoiler: he could single-handedly destroy the entire S-Class, and is able to ''briefly'' tangle with Saitama.]] Subverted in that [[spoiler: Garou was more of an angry teenager lashing out at "unfairness" than a true villain; he never really ''killed'' any of the heroes, although he did hospitalize a fair few.]]

-->'''Luke Skywalker:''' How did my father die?
-->'''Obi-Wan Kenobi:''' A young Jedi named Darth Vader, who was a pupil of mine until he turned to evil, helped the Empire hunt down and destroy the Jedi Knights. [[MetaphoricallyTrue He betrayed and murdered your father]].

* Vargas in ''VideoGame/FinalFantasyVI'', [[SelfMadeOrphan kills his father]] and master out of the belief that he favored Sabin.

** In ''VideoGame/FireEmblemThreeHouses'', [[spoiler:any student character who joins [[TheEmpire the Adrestian Empire]] during the timeskip becomes this to the Church of Seiros' Officer's Academy. This includes Ashe on Silver Snow and Verdant Wind, Lorenz on all routes other than Verdant Wind, and any Black Eagle you don't recruit on Azure Moon or Verdant Wind (bar [[DeceptiveDisciple Edelgard and Hubert]], who were conspiring against the Church to begin with). There's also a case for the Black Eagles and any student you recruit on the Crimson Flower route, where you side with the Empire, but your influence turns the Empire into an AntiHero faction instead of an unquestionable villain.]]

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[[quoteright:350:[[Franchise/StarWars https://static.tvtropes.org/pmwiki/pub/images/anakin_and_obi_wan.jpeg]]]]
[[caption-width-right:350:[[Film/AttackOfTheClones "Why do I get the feeling]] [[CallForward you're going to be the death of me?"]]]]

->''"Shifu found him as a cub and raised him as his son. And when the boy showed talents in kung-fu, Shifu trained him. He believed in him, he told him he was destined for greatness. It was never enough for Tai Lung. He wanted the Dragon Scroll, but Oogway saw darkness in his heart and refused. Outraged, Tai Lung laid waste to the valley. He tried to take the scroll by force and Shifu tried to destroy what he created... but how could he?"''
-->-- '''Tigress''' about '''Tai Lung''', ''WesternAnimation/KungFuPanda''

->''"A young Jedi named Darth Vader, who was a pupil of mine until he turned to evil, helped the Empire hunt down and destroy the Jedi Knights. He betrayed and murdered your father."''
-->-- '''Obi-Wan Kenobi''', ''Film/ANewHope''

* Inverted in ''WesternAnimation/MenInBlackTheSeries'' where BigBad Alpha was Kay's ''mentor'' until he came across a powerful and illegal alien device that allowed him to assimilate alien body parts.

* ''VideoGame/TheLegendOfZeldaSpiritTracks'': Bryne was an apprentice of Anjean in the Tower of Spirits. He desired power from the good spirits, and when he was not granted it, he left and reached out to serve the King of all Evil, Malladus.

->''"A young Jedi named Darth Vader, who was [[TropeNamers a pupil of mine until he turned to evil]], helped the Empire hunt down and destroy the Jedi Knights. He betrayed and murdered your father."''

[[caption-width-right:350:[[CallForward "Why do I get the feeling you're going to be the death of me?"]]]]

* ''ComicBook/LaQueteDeLOiseauDuTemps'' has Bulrog; a former student of the knight Bragon who turned mercenary and eventually ends up seeking vengeance on his master.

* In ''VideoGame/TheLegendOfZeldaSpiritTracks'', Bryne was an apprentice of Anjean in the Tower of Spirits. He desired power from the good spirits, and when he was not granted it, he left and reached out to serve the King of all Evil, Malladus.
* Demolitions expert Peter Stillman accidentally gives rise to ''VideoGame/MetalGearSolid2SonsOfLiberty'''s MadBomber, Fatman (real name unknown), a wannabe public enemy who has turned his knowledge toward terrorist bombings. Like any good ''Star Wars'' yarn, Stillman is cut down by one of Fatman's booby traps, leaving the callow, blond hero to finish the job.

* The ''Franchise/MortalKombat'' series has Frost, a Lin Kuei assassin and cryomancer that Sub-Zero took under his wing, until she decided to try and kill him so she can take control of the Lin Kuei for herself. In ''VideoGame/MortalKombat11'', she turns to evil and joins Sektor and Kronika, voluntarily turning herself into a Cyber Lin Kuei and leading the Tekunin, overseeing the horrific process of [[UnwillingRoboticization turning Lin Kuei into cyborgs]]. When he sees her again, Sub-Zero is visibly disgusted at what his once-protegee has become.
* Uther Lightbringer and Arthas Menethil in ''VideoGame/{{Warcraft}} III'' were much like Obi-Wan and Anakin. Arthas is driven to harsher and eviler tactics to defeat the Undead Scourge over the course of the Human campaign, ultimately taking up the cursed blade Frostmourne and becoming the Death Knight we all know and love and killing Uther during the Undead campaign.
* In ''VideoGame/WarOfOmens'', Listrata dedicates her life to the task of avenging her parents death. Step 1 of that plan is conquering an island chain (the Phenetik islands) as a thesis. However, her mentor, Ashkar views Listrata as a thug for her treatment of the Phenetikians during her conquest.

* In ''Animation/KungFuWa'' Manipulens, the show's big bad, used to be Kung Fu Sock Master's student, but his thirst for power and impatience made him betray him and try to steal the [[MacGuffin Ancient Scroll]], in flashbacks is implied that he didn't cared for his master always wanted to become powerful.

* In ''Animation/KungFuWa'' Manipulens, the show's big bad used to be Kung Fu Sock Master's student, but his thirst for power and impatience made him betray him and try to steal the [[MacGuffin Ancient Scroll]], in flashbacks is implied that he always wanted to gain power.